9mm or 7mm??

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Amartin

9mm or 7mm??

#1 Post by Amartin » Tue Jun 19, 2012 12:01 pm

Hi guys,
yet more advice im hunting for.
Ive got a 40mm EP & a 2x barlow celestron omni series. I also have a 25mm celestron xcel lx. Would a 9 or 7mm xcel lx complete my EP requirements for closer focused views, or am i wasting £65???


Also, on a totally seperate matter, i have on my hand controller a function that allows me to plug in an R232 adaptor & hook up my scope to a laptop. What would this do for me? is it for guiding/alignment from software like stelllarium???

Cheers
Andy

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rwilkinson
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Re: 9mm or 7mm??

#2 Post by rwilkinson » Tue Jun 19, 2012 12:24 pm

First have a try with your 25mm eyepiece and Barlow combination: that should give an effective focal length of 12.5mm and thus a magnification of 120x with your 1500mm focal length.
The very short focal-length (<10mm) eyepieces tend to be tricky to use: you need to position your eye very precisely to see the image; it's more comfortable using a longer eyepiece with a Barlow.
I've had a 6.5mm eyepiece for ages but never use it with my 2000mm 'scope, however it works very well with our ED refractor (555mm focal length) - and when the seeing is very steady I can even add the Barlow-lens too.

Yes, it's possible to control the mount via the RS232 socket with programs such as Stellarium and Cartes du Ciel, as I demonstrated at our Tutorial in May.
I've made up a USB interface lead to facilitate this:
http://www.boltonastro.org.uk/forums/vi ... f=17&t=268
Last edited by rwilkinson on Tue Jun 19, 2012 2:13 pm, edited 2 times in total.

Amartin

Re: 9mm or 7mm??

#3 Post by Amartin » Tue Jun 19, 2012 1:29 pm

Thanks for that Ross, I (wrongly) assumed that the higher the power of the EP the clearer, more focused the view in the EP.
Will give the link to the laptop a go next time we have a clear night
Cheers
Andy

bholmes

Re: 9mm or 7mm??

#4 Post by bholmes » Tue Jun 19, 2012 6:05 pm

Hi Andy.
I bought RS232 leads for my Meade SCT and Celestron Nexstar 127 Mak. They were both under £20 but you will need an extensionto get a comfortable length of cable for manouvering (and come winter sitting indoors with the scope out!). I had problems sourcing the Celestron part as it appears that even the distributors are out of stock but manged to get one from 365 Astronomy. I wish I had known about Ross's gizmo, that will teach me to check out the members area in future.

I have connected both scopes via Stellarium and watched the scopes slew but I have not had chance to try it in anger. That was the plan for tonight but we have a lot of dark clouds around at the moment in Cheshire so I am not that hopeful.

Good look.

Amartin

Re: 9mm or 7mm??

#5 Post by Amartin » Tue Jun 19, 2012 8:49 pm

Thanks Bernie,
I've got the lead that shipped with my EQ5 & I've got a USB to RS232 lead, do indeed anything else like Ross's lead?
Cheers
Andy

bholmes

Re: 9mm or 7mm??

#6 Post by bholmes » Wed Jun 20, 2012 4:35 pm

Hi Andy,
Only a USB cable extension if required.

I had to download Stellarium Scope (http://www.bytearts.com/stellarium/) and ASCOM Platform (http://ascom-standards.org/Downloads/Index.htm) but you may already have these. Once loaded I simply rebooted my PC, connected and swithced on the scope then started Stellarium. Recall having to tell it which port to use but Stellarium found the scope alright which you just select and off you go.

As I said not really used it in anger and got too engrossed in Saturn last night to use Stellarium but I will have a play with it this evening. I think that I found a tutorial on the Web so I will have a look for this and let you know. Sorry if this is not too methodical, it was my typical poke and hope approach but it worked fine.

Regards

bholmes

Re: 9mm or 7mm??

#7 Post by bholmes » Wed Jun 20, 2012 4:46 pm

Hi Andy,
This is what I found on the web,(http://www.astronomyshed.co.uk/forum/vi ... ?f=19&t=44) it mentions another piece of software, EQASCOM.

Regards

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